1. Field of the Invention
This invention relates to a pivotably opening and closing hinge apparatus that connects two devices and particularly to a hinge apparatus that supports an opening and closing automatic document feeder equipped over the original platen or the cover placed on the original platen established on the upper surface of a photographic copying machine; a facsimile apparatus or an image scanner (called image forming apparatus below).
2. Description of the Related Arts
Image forming apparatuses have a clear glass platen plate (called platen below) that comprises the original platen through which light is radiated from below to reflect off of an original document so that the reflected image can be obtained to form an image of the original placed on that platen. It is not unusual for an operator to place one sheet of an original or to place a thick book on the platen for photocopied reproduction. In either case, it is essential to the clarity and the quality of the reproduction of the original to prevent the excessive diffusion of light outside of the image forming apparatus by using a covering body or a cover to push and press the original securely against the platen.
Ordinarily, platen covers are attached to the upper part of the image forming apparatus using a hinge. Ordinary hinge mechanisms have a first attachment plate that is firmly attached to the image forming apparatus and a second attachment plate that is firmly attached to the platen cover that pivot around a common rotating axis. In this construction, the platen cover pivots around this axis to allow the platen cover to open and close with respect to the top of the platen.
It is not uncommon that the platen cover also has functions that are often associated with an automatic document feeder wherein such an apparatus is mounted onto the image forming apparatus to enable the consecutive feeding of a plurality of unbound and loose sheets one sheet at a time to the platen of the image forming apparatus. In such a case, the automatic document feeder itself also performs the essential function of the platen cover.
It should be understood that when an operator wants to use an image forming apparatus to copy specific pages from a relatively thick medium such as a book, the ordinary hinge mechanism just described, namely of a cover or an automatic document feeder mounted onto an image forming apparatus, can only apply a pushing pressure to one edge of the thick original, or book, to hold it in place against the platen of the image forming apparatus which will damage the binding of a book. Of course, if the operator should apply too much pressure from above onto the cover or the automatic document feeder to more completely cover the medium and thereby attempt to prevent unwanted diffusion of light, there would be an unequal distribution of pressure on the platen which will result in the damaging or even the cracking of the platen.
Thus, in order to alleviate such unwanted situations that result from the two piece construction of an automatic document feeder mounted to an image forming apparatus, it is desirable to arrange the structure of one device (hereinafter called xe2x80x9cplaten coverxe2x80x9d) with respect to the other device so that it can apply an equal pressure over the entire back side of a thick book by being parallel with respect to platen.
There have been opening and closing hinge apparatuses that move the platen cover into a vertical and parallel position above the platen.
An example of the prior art is disclosed in Japanese Patent Application Disclosure No. Hei 5-9597. The hinge apparatus (hereinafter called xe2x80x9cfirst artxe2x80x9d) described is shown in FIGS. 15A to 15D. The first art shown in FIG. 15A comprises the attachment frame 302 which is attached to the copy machine 301 and the movable hinge 304 which is attached to the platen cover 303. The rising and lowering hinge 306 pivotably supports the movable hinge 304 on the shaft 305 and the parallel link arms 307 and 308 are connected to allow the rising and lower hinge 306 to move vertically with respect to the attachment frame 302. One end of each of the parallel link arms 307 and 308 is attached to the attachment frame 302 by shafts 309 and 310 respectively, and the other ends of each of the parallel link arms 307 and 308 are attached to the rising and lowering hinge 306 by the shafts 311 and 312, respectively. As can be seen in FIGS. 15(A) through (D), when the platen cover is opened by operating the platen cover hinge 303 to copy a thick document 313, the inner side of the platen cover pushes on the outer edge of the thick document 313 as the operator opens the platen cover by lifting. This pivots the platen cover on and around the line of the point of contact by pushing on the edge of the thick document 313. In the system as described for the hinge mechanism related to the first art, the rising and lowering hinge 306 is attached to the frame 302 using the parallel links 307 and 308 so the vertical movements of the parallel links 307 and 308 have substantially the same circular action. Thus, it is possible to attain the smooth upward movement of the rising and lowering hinge 306 only if the rotational force of the platen cover 303 is transmitted to the rising and lower hinge 306 using the thick document 313.
This hinge structure unifies the lifter mechanism by connecting the rising and lowering hinge 306 to the attachment frame 302 with the parallel links 307 and 308 thereby making it possible to provide a single hinge apparatus which encompasses both the opening and closing functions and the lifter function.
Another hinge apparatus (called xe2x80x9csecond artxe2x80x9d below) is disclosed in Japanese Patent Application No. Hei 61-20587 disclosed in the prior art as a document holder capable of opening and closing. This hinge apparatus, as can be seen in FIG. 16, comprises the lifter 351 which is attached to the copy machine 350 and the hinge 352 which is attached to the lifter 351. The platen cover 353 can be opened and closed with the hinge 352. The lifter 351 is composed of the base plate 354 and the paired first rising and lowering arms 355 and 356 which are attached to base plate 354 so that the platen cover 353 is vertically movable in the direction of opening and closing. The paired second rising and lowering arms 357 and 358 are movably attached to the free end of both the paired first rising and lowering arms 355 and 356 and the bracket 359 is attached to the free ends of the paired second rising and lowering arms 357 and 358. This bracket 359 employs the attached structure of the hinge 352. It is possible with this particular structure for an operator to place a thick book onto the platen without the front end of the platen cover remaining at an angle. This structure allows the complete and parallel covering of the upper surface of the book. It is also important to note that the structure of this apparatus prevents the platen cover from bending and it prevents the diffusion of light to outside of the photographic copy machine and the infusion of light into the internal optical system.
However, in the hinge apparatus of the first art just described, the pressing action of the platen cover 303 causes the lift mechanism to continue functioning while the edge of the book and the platen cover 303 are in contact. Thus, the thickness and the positioning of the book on the platen induce the book to move and become displaced in the left and right directions of FIG. 15C. Such a force generated by this movement presents the unwanted possibility of bending or otherwise damaging the pages that are in contact with the platen or causing the book to become mis-positioned. In this hinge apparatus, there is no systematic relationship between the movements of the hinge 306 and the lift action so when the operator is opening or closing the platen cover 360, he or she must perform the separate and unrelated actions of opening or closing the platen cover 360 and then operating the lift. These make the operation of the platen cover 360 a more complex task when the copying of a thick book is desired.
Also, in the platen cover hinge apparatus described above as the second art, there is an excessive cost because of the duplicative construction of each of the parts which are independently structured to enable the lift mechanism which uses a jack method to raise and lower the hinge for the opening and the closing actions. Also, because the operator must perform the action of opening or closing the platen cover and the action of lifting the entire platen cover, as is also the case with the first art, the operation of the platen cover is a more complex task and therefore it is more difficult.
It is an object of the present invention to provide a hinge apparatus that can perform both the rotating function along with a rising and lowering action to allow the platen cover to cover the thick book original both horizontally and parallelly without damaging the book or causing mis-positioning of the book.
It is also an object of the present invention to provide a hinge apparatus that is capable of pivoting open, and that is also capable of rising and lowering parallel to the copy machine body in one easy operation.
Another object of the present invention is to provide a hinge apparatus which is of a simple construction and which enables a platen cover to pivotally rotating open and to rise and lower parallel to the copy machine body in one easy operation.
In order to attain the objectives of the hinge apparatus, the present hinge apparatus that connects two bodies and opens and closes comprises an arm member pivotably attached to one of either of two bodies and an arm member connected to the other of the bodies. The first and second paired link members are equally spaced from each other and the bases of the arm members are pivotably attached to the apparatus body. The paired link members pivot in the same direction on their ends spaced apart in the direction of the pivot.
Also, the distances of the paired link members in the pivoting direction and the lengths of the link members substantially form a parallelogram.
There is also a means for restricting the opening and closing movement of at least one side of the pivoting movement of said arm member and the pivoting movement of said link arm member.
At the point where the platen cover is rotating from an open state to a closed state, a restricting means restricts the movement so that the first arm member will rotate, then the link member will rotate.